Quick coupling devices are known that comprise a tubular insert possessing means for anchoring it permanently in the rigid element, means for retaining the end of the pipe, and a sealing gasket. The anchoring means are generally implemented in the form of a spigot with serrated tangs formed on the outside surface of the tubular insert in order to oppose the insert being withdrawn axially once it has been inserted into a bore of the circuit element. The retaining means are generally implemented in the form of a washer having inwardly-directed teeth, in which the teeth (or claws) are lifted by bending during insertion of the end of the pipe into the tubular insert, and subsequently tend to bite into the pipe in order to opposite extraction thereof. The sealing gasket, generally an O-ring, is associated with the tubular insert in such a manner as to be compressed between the wall of the bore and the outside surface of the end of the pipe.
When the coupling is to be subjected to high levels of stress, for example when it is implanted in a circuit where a fluid flows at a relatively high pressure, the washer used is very stiff so as to be able to oppose large extraction forces. Nevertheless, there exists a risk of the end of the pipe flattening slightly so that not all of the teeth in the washer bite correctly into the outside surface at the pipe end. This phenomenon can result in particular from the pipe end being ovalized due to a bending force being exerted on the pipe from outside the coupling.
To obviate that drawback, proposals have been made to support the pipe end by means of a rigid bushing that is inserted therein.
Quick coupling inserts or cartridges provided with an internal bushing are known, in particular from documents U.S. Pat. No. 5,673,942 and DE 198 00 050.
The question which remains poorly solved by those known devices is the question of sealing the coupling, which generally requires either two sealing elements to be provided or else the element in the bore to be provided with a gasket independent of the cartridge, which goes against the concept of a cartridge coupling.